Dipstick



July 9, 1940. WARREN 2,207,526

DIPSTICK Filed April 28, 1938 r 2.

a J 7 5 5-7 a v 4 a J 5 INVENTOR. 1 1% P0261 B. Mrren ATTORNEYS 1 Claim.

Patented July 9, 19 40 DIPSTICK Harold B. Warren, Detroit, Mich., assignor to Thomson-Gibb Electric Welding Company, Lynn, Mass, a corporation of Massachusetts Application April 28, 1938, Serial N0. 204,818

This invention relates to a dipstick which is particularly adapted for use in connection with the crankcase of an internal combustion engine for indicating the amount and the condition of the oil in the crankcase. It is customary in internal combustion engines, particularly automobile engines, to provide the crankcase with an opening above the level of the lubricating oil in the crankcase through which a dipstick is inserted downwardly into the oil in the crankcase. The dipstick is usually provided with graduations or other suitable markings which indicate by means of the oil line left on the dipstick after withdrawal from the crankcase the amount of oil in the crankcase.

The dipstick upon being withdrawn from the oil is covered with a very thin film of the oil. By visual examination of this thin film of oil on the dipstick one can roughly determine the condim tion of the oil, that is, whether it is clean or dirty, and thus make a rough determination whether or not the crankcase oil should be exchanged for clean oil.

Since dipsticks are usually made of iron or steel which corrode and turn black after short usage, it has heretofore been proposed to weld an indicating strip of metal on the face of the dipstick which has lithographed or otherwise printed on it in black letters the word cleanf upon a background substantially the color of a film of clean oil. Upon immersing this dipstick in the crankcase oil and withdrawing the stick a thin film of oilis deposited on the strip over the word clean. The degree of visibility of the word clean against the background determines the amount of dirt or discoloring matter in the film of oil. When the word clean is not visible through the oil film, then the oil is dirty. The difficulty with this dip-stick arrangement is that the film of oil which adheres to the indicating strip is so thin that the oil film appears clean when actually the oil contains considerable dirt or discoloring deposits.

Another diificulty with this dipstick is that during the insertion and withdrawal of the dipstick into and out of the crankcase the'lithographed strip rubs against the sides of the opening in the crankcase and the lithographed word clean is worn away until it ceases to be visible.

The objects of this invention are to overcome the above-mentioned defects in dipsticks. The first of these objects have been achieved by arranging the dipstick so that a thicker film of oil is retained on the dipstick over the lithographed strip and particularly over the area containing the word clean whereby the dirt and discoloring matter in the oil is more easily seen and the condition of the oil in the crankcase more accurately determined. The second of these objects has been obtained by protecting the strip and particularly the printed area of the same from rubbing against the sides of the openings in the crankcase. r

These objects have been achieved by forming the end of the dipstick which is adapted to be immersed in the crankcase oil in'the form of a trough in which is secured the printed strip of metal, the trough serving not only to retain a thicker film of oil, as above described, but also serves as a guard which protects the printed strip from rubbing against the sides of the openings in the crankcase.

In the drawing:

Fig. 1 is aside elevation of the dipstick.

Fig. 2 is a front elevation of the dipstick looking into the trough.

Figs. 3, 4, 6 and 7 are sections along the lines 3-3, 44, 6-6 and 'I-'l of Fig. 2.

Fig. 5 is a sectional view showing the printed indicating strip inserted in the trough before the side walls of the trough have been turned inwardly to retain the strip in place.

Referring more particularly to the drawing the dipstick comprises three members, the wire handle member I having the looped end 2, the stamped channel member 3, the lower end of which is adapted for immersion in the crankcase oil, and the indicating strip 4.

The handle member I is preferably formed from spring steel wire and provided adjacent one end with an offset portion 5. The stamped channel member 3 is also provided with an offset por tion 6. The end of the wire handle I is inserted in the channel member 3 with the oifset portion 5 opposite the offset portion 6 of the channel 3 and the channel is then pressed on to and about the wire member at the ends of the offset portion 5 as at 1 and 8 to fix the wire handle member tothe trough member. In addition, although not essential, the wire member I and trough member 3 can be welded or soldered together at points 1 and 8. The offset portions 5 and 6 serve as a friction latch for retaining the dipstick in the opening in the crankcase. Upon insertion in the opening in the crankcase the portions 5 and 6 engage the wall of the opening and are stressed thereby. The inherent resiliency, particularly of the ofiset portion 5 upon being stressed by the opening in the crankcase, frictionally retains the dipstick in the opening in the crankcase.

Initially the member 3 takes the form of a trough of channel portion shown in section in Fig. 5, consisting of the base 9 and the upstanding side walls ill. The base 9 and the upstanding walls It] cooperate when the dipstick is immersed in oil and withdrawn to retain a much thicker film of oil in the trough than is possible with the presently used flat strip.

To facilitate the visual examination of the oil to determine its condition, the film of oil in the trough preferably should be carried upon a surface which will show the impurities and discoloring matter in the oil film. This surface or background for indicating the condition of the oil against which the film of oil is examined can be obtained in various ways. Any background can be used which will show up the dirt in the oil. Thus the background can be any color or shade other than the color or shade of the dirt in the oil, for example, a white background and abackground the color of the clean oil film have been found suitable. Preferably the trough member 3"is made of a cheap metal or alloy, such as steel, and provided with a facing preferably in the form of the metal strip 4. The flat strip 4 has lithographed or" otherwise printed thereon the word clean, preferably in'black ink against a background of any. color or shade which will show up the dirt in the oil. After the strip has been laid in the trough 9; the side walls H], as shown in Fig. 6, are turned inwardly over the side edges of the strip 4 merely a sufficient distance to prevent the strip from falling out of the trough. Addi tional means are provided for retaining the strip 4 in the trough, particularly for retaining the strip 4 against slippage in the trough, by indenting or deforming the side walls of the trough and the strip 4 at opposed points II. This deformation of the side walls of the trough and of the strip 4 looks the two together.

It will be seen, particularly from Fig. 6, that in the finished form of the dipstick the side walls I I] of the trough project above the strip 4, and particularly the lithographed face of the strip 4, thus preventing any contact between the lithographed face of the strip 4 and the walls of the opening in the crankcase. Further, in the finished form of the dipstick, the side walls I 0 in the trough cooperate with the strip 4 and base 9 to retain a much thicker film of oil'over the strip 4 than is possible with an ordinary flat strip.

I claim:

A dipstick for indicating the condition of the oil in the crankcase of an engine adapted for insertion into the crankcase through an opening in the crankcase comprising a metal stamping in the form of a trough adapted to be immersed in the oil and a handle in the form of a resilient wire secured at spaced points to the said trough, the

portion of the wire between the points of securemerit being offset whereby the offset resilient wire portion cooperates with the trough to serve as a friction latch for frictionally engaging the opening in the crankcase to retain the dipstick in the crankcase.

HAROLD B. WARREN. 

